1. Field of the Invention
The present invention relates generally to a home network, and more particularly to a system and method for transmitting and receiving a call on a home network by using UPnP (Universal Plug and Play).
2. Description of the Related Art
In general, a home network is created using an Internet protocol (IP)-based private network. Such a home network connects and controls various devices, such as all kinds of Personal Computers (PCs), intelligent appliances, and wireless devices, to a single network through a common virtual computing environment, often referred to as “middleware”. Middleware enables various devices to communicate with each other by interconnecting them in a peer-to-peer manner. Some of the middleware proposed to date includes Home Audio/Video (AV) Interoperability (HAVI), Universal Plug and Play (UPnP), Java intelligent network infrastructure (Jini), and Home wide web (HWW).
Among these and others, a UPnP network is currently the most widely used home network technology, and defines a UPnP device, a UPnP service, and a protocol between the UPnP device and the UPnP service.
The UPnP network includes Controlled Devices (CDs) that are home network devices connected to and controlled by an IP-based home network, and a Control Point (CP), which is a device for controlling the CDs.
The CP transmits a request for an event to each of the CDs, and receives the requested event from each of the CDs. Each of the CDs then performs a given function at the request of the CP. If the state of a CD changes, the CD transmits a requested event to the CP having requested the event.
The UPnP devices perform advertisement, discovery, description, control, and eventing processes. More specifically, in the advertisement process, a new CD is connected to a home network, and advertises its existence to other devices on the home network. In the discovery process, a new CP is connected to the home network, and searches CDs operating on the home network. In the description process, the CP determines the functions of newly added devices by parsing service description Extensible Markup Language (XML) files or device description XML files through IP addresses of the searched CDs in order to control the CDs. In the control process, when the CP is to provide a specific service through a CD, it transmits an action request for the specific service to the corresponding CD, using Simple Object Access Protocol (SOAP) according to the UPnP Device Architecture (UDA), and receives a result (variable value) in response to the transmitted action request. Additionally, the eventing process checks the information change state of the CD that has provided the specific service at the CP's control command.
Based on the above UPnP network technology, UPnP AV technology has been developed, which enables enjoyment of multimedia contents, such as music, video, movie, etc. For more reference, the UPnP AV technology is described in the UPnP AV specification.
According to the UPnP AV specification, the UPnP AV architecture includes a media server for providing a multimedia file through a Content Directory Service (CDS), a media renderer for rendering the provided multimedia file, and a CP for controlling the media sever and the media renderer to interact with each other. The CDS is an embedded service of the media server, and provides the CP with metadata of contents that exist inside or outside of a home network and are stored in the media server. The CP identifies the metadata provided from the CDS, and requests the media renderer to render the identified metadata. Accordingly, when a terminal exists on a home network, the corresponding terminal retransmits calls, which are transmitted to the terminal through a Video and Voice Over IP (VVOIP) and a mobile communication system, into the home network, using the above UPnP AV architecture.
However, because the conventional UPnP AV architecture was developed for searching, moving, and synchronizing contents on a home network, it has a problem in controlling various call control signals used in a telephone call system. In addition, because the conventional UPnP AV architecture does not include an answering feature and a Short Messaging Service (SMS) writing or sending function, it is incapable of using these functions.
Further, because the conventional UPnP AV architecture is used in transmission of AV contents, it includes parts that are unnecessary when call voice and video are transmitted.